The instant inventions relates, generally, to the field of direction finding transmitter and receiver, and, more specifically, to systems designed to track subjects under surveillance.
At the present time parents and other caretakers are particularly concerned that their charges may be in danger if the charge wanders beyond the audible or visual field of view of the caretaker. One solution that is frequently employed is to tether the charge to the caretaker by physical means such as a strap with buckles. However, this technique unnecessarily restricts the range of movement of the charge, the strap can tangle and even choke an individual.
A better technique is required that would allow a subject under surveillance considerable freedom of movement while sounding some alarm when the distance between the subject under surveillance and the observer exceeds some preset limit.